Optical formation device and method

ABSTRACT

The purpose of the invention is to provide a solid model creation apparatus that is small in size and inexpensive. A multiplicity of blue LEDs are prepared, optical fibers are connected thereto, and GRIN lenses are arranged at the ends of the tips of the respective optical fibers to constitute an exposing head  23.  The exposing head  23  forms images of the end faces of the respective optical fibers in a photocurable resin exposure region  24  as light spots  55.  The diameter of a light spot  55  is, for example, 0.5 mm, but the size of a pixel  71  within the exposure region  24  is much smaller; for example, 62.5μ. The multiplicity of optical fibers at the exposing head  23  are arrayed in a matrix such that they are displaced in staggered fashion so that respective light spots  55  are lined up at the pitch 62.5μ of the pixels  71  in the primary scan (Y-axis) direction. As the exposing head  23  scans the exposure region  24  in the secondary scan (X-axis) direction, all of the light spots capable of directing light onto appropriate pixels, these being the respective pixels  71  to be cured within the exposure region  24,  are turned on and multiple exposure is carried out.

TECHNICAL FIELD

The present invention pertains to a solid model creation apparatus forcreating models having three-dimensional shapes using photocurableresin.

TECHNICAL BACKGROUND

A great many inventions are known with respect to solid model creationapparatuses, these including, for example, Japanese Patent No. 1827006.Conventional solid model creation apparatuses generally employ as lightsource a gas laser generator outputting ultraviolet laser light.

Gas laser generator size is fairly large (e.g., 150 cm×30 cm×30 cm), andconsequently solid model creation apparatus main body size is likewisecorrespondingly large. In addition, the gas laser generator is itselfexpensive, and moreover, depending on the type of generator, a 200 Vpower supply and a water cooling apparatus (chiller) may well berequired. Accordingly, the price of a conventional solid model creationapparatus is extremely high (e.g., several tens of millions of yen).

Accordingly, the object of the present invention is to provide a solidmodel creation apparatus that is small in size and inexpensive.

DISCLOSURE OF THE INVENTION

The solid model creation apparatus with which the present invention isconcerned is equipped with a tank that holds a photocurable resinsolution, an exposure region set within the photocurable resin solutionin the tank, an exposure apparatus that irradiates light onto thisexposure region, and a control apparatus that controls the exposureapparatus so as to cure selected pixel(s) within the exposure region.The exposure region may be defined as a two-dimensional set of amultiplicity of pixels fine enough to satisfy requirements fordimensional accuracy in a solid model. The exposure apparatus possessesat least one light spot generator that is capable of being switched onand off and that irradiates the exposure region with a light spot whenturned on. The size of each light spot with which the exposure region isirradiated is larger than each pixel in the exposure region.Furthermore, the exposure apparatus scans the exposure region with thelight spot generator, and throughout the course of this scanning thecontrol apparatus turns on the sum total plurality of light spotgenerators present at locations permitting irradiation of the selectedpixel with the light spot.

“Sum total plurality” as used here is meant to include not onlysimultaneous irradiation of the same pixel with a plurality of lightspots from a plurality of physically different light spot generators,but also repeated irradiation of the same pixel with light spotsgenerated by a single physical light spot generator at different timesduring scanning.

The size of the light spot irradiated on the exposure region from alight spot generator in the solid model creation apparatus of thepresent invention is not as small as an exposure region pixel, butrather is larger than the pixel. Furthermore, because exposure of eachpixel is carried out in multiple fashion using a sum total plurality oflight spots, the output of each light spot generator may be relativelylow. It is therefore not necessary that a conventional large andexpensive gas laser generator be employed as light source in the lightspot generator, it being possible to employ a small and inexpensivesolid-state luminescent element such as an LED therefor. As a result, itis possible to provide a solid model creation apparatus that is far moreinexpensive than was the case conventionally (e.g., on the order ofseveral millions of yen as opposed to several tens of millions of yen,as was the case conventionally).

From the standpoint of exposure efficiency, it is desirable that therebe a plurality of light spot generators. In such a case, in order topermit multiple exposure as described above, it is desirable that theapparatus be constituted such that the light spots from the plurality oflight spot generators are arrayed in the primary scan direction at afirst pitch (typically the pixel pitch) which is smaller than thediameter of the light spots at the exposure region, and the exposureregion is scanned in the secondary scan direction with that plurality oflight spots. Furthermore, it is still more desirable that a multiplicityof light spots be arrayed across the entire length of the exposureregion in the primary scan direction.

As described above, in arraying a plurality of light spots at a smallfirst pitch, a plurality of light spot generator subarrays, eachcomprising two or more light spot generators lined up in a single row inthe primary scan direction at a second pitch which is the same as orgreater than the light spot diameter may be provided, and these lightspot generator subarrays may themselves be arranged in the secondaryscan direction with a displacement therebetween in the primary scandirection which is equal to the aforesaid first pitch. Adoption of suchan arraying method makes it possible for large light spot generators tobe arrayed in the primary scan direction at the first pitch even whenthe size of each of those light spot generators is much larger than thefirst pitch.

In order to permit the aforementioned multiple exposure, a controlapparatus may control the exposure apparatus as follows. To wit, thecontrol apparatus first receives data indicating the cross-sectionalprofile of a solid model and expands the cross-sectional profile byapplying a prescribed offset to this data. Next, while light spotgenerator(s) are scanning the exposure region, the control apparatusturns on light spot generator(s) for which the center of the lightspot(s) therefrom are located at respective pixels contained within theexpanded cross-sectional profile. A method incorporating this offsetexpansion processing makes it possible to carry out effective multipleexposure of all pixels within the cross-sectional profile of a solidmodel (in particular, not just the pixels at the interior of the profilebut also pixels in the vicinity of the outline thereof) by merelycarrying out a simple light spot drive method wherein respective lightspot generators are turned on and off in accordance with the value ofthe pixel at the center of the light spot therefrom.

As mentioned above, a solid-state luminescent element such as an LED maybe employed as light source in the respective light spot generators. Itis desirable that the apparatus permit a constitution wherein an opticalfiber is connected to each LED, and that a light spot from the tip ofthat optical fiber irradiate the plane of exposure. It is furtherdesirable that the apparatus permit a constitution wherein a GRIN lens(gradient index lens; graded refractive index lens) is arranged at theend of the tip of the optical fiber, and the image of the tip of theoptical fiber is formed on the exposure region. Such a constitution willmake it possible to produce a light spot having a small diametercorresponding to the diameter of the optical fiber (e.g., 0.5 mm). Useof a light spot on this order of smallness will permit creation of solidmodels having dimensional accuracies adequately permitting practical usefor typical solid model creation applications. In addition, the solidmodel creation apparatus of the present invention possesses an extremelylarge practical advantage because price is lowered to the extent that itis of a different order of magnitude in comparison with conventionalsolid model creation apparatuses employing gas lasers, and because theapparatus is also made small in size.

It is desirable that the LED serving as light source emit light ofwavelength as high in energy (i.e., as short in wavelength) as possible,and from this standpoint it is desirable that a blue LED be used, orthat an ultraviolet LED be used if one is available.

Moreover, the LED used as light source may be integral with the lightspot generator (exposing head) which scans the exposure region such thatit moves together with the exposing head, or the apparatus may beconstituted such that the LED is secured at a location removed somedistance from the exposing head and is linked to the exposing head bymeans of an optical fiber, such as is the case in the embodiment to bedescribed below.

The present invention also provides a solid model creation method. Inthis method, while a photocurable resin exposure region is being scannedby at least one light spot larger in size than a pixel therein, a lightspot capable of irradiating a selected pixel is turned on, as a resultof which a sum total plurality of light spots are directed at theselected pixel and multiple exposure is carried out. Such a methodpermits practical solid model creation to be carried out using a lightspot generator that, for example as with the aforementioned combinationof LED and optical fiber, while capable of generating only a light spotlarger than a pixel and wherein moreover light spot output is small, isnonetheless small in size and extremely inexpensive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the overall constitution of a solidmodel creation apparatus associated with an embodiment of the presentinvention.

FIG. 2 is an oblique view showing the external appearance of an exposinghead 23.

FIG. 3 is a side view showing the constitution of an individual LED.

FIG. 4 is a plan view showing an example of arrayal of optical fibers 55at an exposing head 23.

FIG. 5 is a plan view showing another example of arrayal of opticalfibers 55 at an exposing head 23.

FIG. 6 is a plan view showing the relationship between a single lightspot 59 projected onto the resin solution surface from a single opticalfiber 55 and the pixels 71 in the exposure region.

FIG. 7 is a plan view showing the principle behind multiple exposure.

FIG. 8 is a flowchart showing processing performed by a control computer3.

FIG. 9 is a plan view showing coordinates of arrayed optical fibers andcoordinates of pixels for the purpose of describing a method by which aluminescent pattern is created.

FIG. 10 is an oblique view showing another LED light sourceorganizational scheme.

BEST MODE OF CARRYING OUT INVENTION

FIG. 1 shows the overall constitution of a solid model creationapparatus associated with an embodiment of the present invention.

This solid model creation apparatus 100 possesses an apparatus main body1 comprising mechanisms necessary for solid model creation, a lightsource, and drive apparatuses therefor; and a control computer 3 forcontrolling operation of this main body 1. The control computer 3 may beconnected by way of “Ethernet” or other such telecommunications network9 to a three-dimensional CAD system 5, a workstation 7 for generation ofcontrol data, and so forth. The three-dimensional CAD system 5 performsthree-dimensional modeling of a solid model and generatesthree-dimensional profile data for the solid model. The workstation 7for generation of control data slices this three-dimensional profiledata into a multiplicity of thin layers, generates a two-dimensionalprofile for each layer, and supplies this two-dimensional profile datafor each layer, thickness data, and so forth to the control computer 3.

Installed within the apparatus main body 1 is a resin solution tank 11,this being filled to a prescribed level with photocurable resin solution13. In order to control solution level, a solution surface detectingsensor 31 detects the solution level, the control computer 3 controls asolution surface adjustment drive apparatus 35 based on this detectionsignal, and in accordance with this control the solution surfaceadjustment drive apparatus 35 causes operation of a solution surfacelevel adjustment volume 3.

Within the resin solution tank 11 there is a Z-axis elevator 15, a tray19 being placed above this elevator 15. The elevator 15 can be made tomove in the Z-axis direction (vertical direction) by means of Z-axiselevator drive apparatus 21, which is controlled by the control computer3. As is commonly known, the elevator 15 is gradually lowered as thesolid model 17 is formed on the tray 19 during solid model creation.

An exposing head 23 which irradiates the solution surface with light forcuring is arranged over the solution surface above the tray 19. As shownin the oblique view of FIG. 2, the exposing head 23 is long in theY-axis direction and can be made to move in the X-axis direction bymeans of a scan-axis drive apparatus 25, which is controlled by thecontrol computer 3. The exposure region 24 covered as the exposing head23 moves is, in this embodiment, 64 mm in the X-axis direction and 64 mmin the Y-axis direction, and the maximum planar size of the solid model17 that can be created is therefore 64 mm×64 mm (however, as a result ofexpansion due to application of an offset, to be described below, themaximum planar size of the solid model 17 that can actually be createdwill be approximately 60 mm×60 mm). The exposing bead 23 is connected toan LED light source 37 by way of an optical fiber bundle 39. Thedetailed constitution of this part of the apparatus will be describedbelow.

Arranged adjacent to the solid model 17 plane of exposure (solutionsurface) is a recoater 27, which is long in the Y-axis direction andwhich is for the purpose of flattening that plane of exposure (solutionsurface). The recoater 27 can be made to move in the X-axis direction bymeans of a recoater drive apparatus 29, which is controlled by thecontrol computer 3.

In order to control the temperature of the resin solution 13,temperature sensors 41, 43 detect the temperature of the resin solution13 at a plurality of locations, the control computer 3 controls atemperature controller 45 based on those detected temperatures, and thetemperature controller 45 drives a heater 47 in accordance with thatcontrol.

Worthy of particular note within the above constitution is the structureof the light source portion thereof (exposing head 23, optical fiberbundle 39, and LED light source 37), and control of that light sourceportion by means of the control computer 3. Below, these points shall bedescribed in detail.

Three-dimensional profile model data created by the three-dimensionalCAD system 5 is sliced into, for example, 0.1 mm-thickness layers in theZ-axis direction. The data for each sliced layer is data defining atwo-dimensional profile in the XY plane and is supplied to the controlcomputer 3 of the solid model creation apparatus 100. The controlcomputer 3 first converts the two-dimensional profile data for eachlayer into 1,024-bit x 1,024-bit bitmap data. This bitmap datarepresents the image of the aforementioned exposure region 24 (64 mm×64mm) in the XY plane. In other words, this bitmap data expresses the 64mm×64 mm image of the exposure region 24 as a 1,024-pixel×1,024-pixelraster image. Accordingly, each bit of this bitmap data corresponds to a62.5-μm×62.5-μm pixel within the exposure region 24, the values “1” and“0” for each bit respectively meaning that the resin should be cured(light source turned on) or not cured (light source turned off) at thatpixel.

LED light source 37 comprises 1,024 LEDs corresponding to the number ofpixels in a single line in the Y-axis direction in the exposure region24. These 1,024 LEDs are capable of being individually turned on and offby means of commands from the control computer 3. FIG. 3 shows theconstitution of an individual LED. As shown in FIG. 3, each LED 51 isconstituted such that the lens region at the head portion of acommercially available LED lamp 53 has been cut away and an opticalfiber 55 connected thereto such that substantially all of the outputlight is incident on the optical fiber 55. It is preferred that each LED53 emit light of wavelength as close to the ultraviolet, as short inwavelength, and as high in energy, as possible, and in this embodimentan LED emitting blue light (wavelength 470 nm, output 3 mW) is used.

The 1,024 optical fibers 55 connected to the 1,024 LEDs 51 within theLED light source 37 are guided to the exposing head 23 as the opticalfiber bundle 39 shown in FIG. 1. At the exposing head 23, the tips ofthe 1,024 optical fibers 55 are arrayed in a configuration such as willbe described below with reference to FIG. 4, and below these there isarranged a GRIN lens plate 57, such as is shown in FIG. 3, wherein amultiplicity of columnar GRIN lenses (graded refractive index lenses)are lain side by side in planar fashion. This GRIN lens plate 57 formsimages 59 of the end faces of the respective optical fibers 55 (i.e.,light spots of the same diameter as the optical fibers 55) on the resinsolution surface therebelow. The diameter of each optical fiber 55 is,for example, 0.5 mm, and the diameter of each light spot 59 imaged bythe GRIN lens plate 57 is therefore also 0.5 mm.

FIG. 4 is one mode of planar arrayal of the ends of the optical fibers55 at the exposing head 23.

The 1,024 optical fibers 55 are respectively for the purpose of exposingthe locations of the 1,024 respective pixels parallel to the Y axis inthe exposure region 24. Accordingly, it is necessary that the tips ofthe 1,024 optical fibers 55 at the exposing head 23 be arrayed parallelto the Y axis at a pitch 62.5 μm which is equal to the pitch of pixelsin the exposure region 24. However, because the diameter of each of theoptical fibers 55 is 0.5 mm, which is much larger than the 62.5-μm pixelpitch, it is impossible to array the optical fibers 55 in a single rowat this pitch.

An arrayal of fibers is therefore adopted, such as is shown in FIG. 4,wherein there are 8 rows of 128 fibers. That is, 128 optical fibers 55are lined up in a straight line in the Y-axis direction at a pitch 0.5mm which is equal to the diameter of the optical fibers, creating asingle optical fiber subarray 63 <1> which is 64 mm in length. The otheroptical fiber subarrays are similarly prepared for a total of 8 opticalfiber subarrays 63 <1> through 63 <8>. In concrete terms, each of theoptical fiber subarrays 63 <1> through 63 <8> may be created byembedding 128 optical fibers 55 in a channel, which is 64 mm in length,of a bed 65. These 8 optical fiber subarrays 63 <1> through 63 <8> arearranged so as to be respectively parallel to the Y-axis direction, andsuch that there is a displacement therebetween in the Y-axis directionof 62.5 μm, which is equal to the pixel pitch, and with a suitablespacing in the X-axis direction (the external appearance of the exposinghead 23 will therefore be such that there are 8 beds 65 lined upthereon, as shown in FIG. 2).

As shown in FIG. 4, scanning of the exposing head 23, whereon the 8optical fiber subarrays 63 <1> through 63 <8> are lined up, in theX-axis direction causes the 1,024 optical fibers 55 thereof torespectively scan the locations of the 1,024 pixels parallel to theY-axis in the exposure region 24. For example, if numbers are assignedto those 1,024 pixels starting from the end thereof, as the 0th, 1st, .. . 1,023rd, then the optical fibers 55 of the first-row subarray 63 <1>shown in FIG. 4, scan the locations of 128 pixels, these being the 0th,8th, 16th, . . . , or every 8th pixel starting from the 0th pixel, whilethe optical fibers 55 of the second-row subarray 63 <2> scan thelocations of 128 pixels, these being the 1st, 9th, 17th, . . . , orevery 8th pixel starting from the 1st pixel.

Moreover, the fiber arrayal shown in FIG. 4 is one example thereof, itbeing possible to employ a different arrayal, such as for example thearrayal shown in FIG. 5. In the arrayal shown in FIG. 5, the twosubarrays are arranged adjacent to each other with a displacementtherebetween in the Y-axis direction equal to the fiber radius of 0.25mm such that what was subarray 63 <5>, the fifth-row subarray in thearrayal shown in FIG. 4, is now arranged next to the first-row subarray63 <1>. Because this arrangement permits minimum spacing in the X-axisdirection between adjacent subarrays, the size of the exposing head 23in the X-axis direction will be a minimum.

FIG. 6 shows the relationship between a single light spot 59 projectedonto the resin solution surface from a single optical fiber 55 and thepixels 71 at that resin solution surface.

As has already been described, the diameter of each of the light spots59 projected onto the resin solution surface by the GRIN lens plate 57is the same as the diameter of each of the optical fibers 55, or 0.5 mm.In contrast thereto, the size of an individual pixel 71 is 62.5 μm×62.5μm. As a result, a light spot 59 irradiates not only a pixel 73 locatedat the center thereof (the pixel described as being scanned byrespective optical fibers 55 at the fiber arrayal description given withreference to FIG. 4), but also a large number of pixels surrounding thiscentral pixel. Looking at this from another point of view, it is clearthat a single pixel 73 is irradiated by a multiplicity of light spotswhich possess centers within this 0.5 mm-diameter range centered on thispixel 73. In the present embodiment, this fact is exploited to carry outmultiple exposure of a single pixel by a multiplicity of light spots soas to make maximum use of the light output from the LED light source.

FIG. 7 shows the principle behind this multiple exposure. As shown inFIG. 7, in curing a certain pixel 73, all of the light spots whichpossess centers at locations of any of the pixels (pixels marked with a“+” in the drawing) within this 0.5 mm-diameter range centered on thispixel 73 are turned on. This multiple exposure is achieved as a resultof the use of the arrayal wherein optical fibers are lined up at thepixel pitch as indicated by way of example at FIG. 4 and FIG. 5, and asa result of application of an offset to the profile of the solid model,to be described below.

FIG. 8 shows the flow of control processing for the purpose of driving alight source having the above-described constitution.

As has already been described, the three-dimensional CAD system 5 firstmodels three-dimensional profile data for the solid model (step S1).Next, the workstation 7 slices the three-dimensional profile at aprescribed pitch in the Z-axis direction, two-dimensional profile datais created for each sliced layer, and this is sent to the controlcomputer 3 of the solid model creation apparatus 100 (S2).

The control computer 3 then applies a prescribed offset to thetwo-dimensional profile data for each layer, and this two-dimensionalprofile is expanded by the amount of this offset (S3). For example, asshown in FIG. 8, if the original two-dimensional profile is a circle 81,an offset 83 is added to the radius thereof to expand it to a circle 85of larger radius. Again, though not shown, if the originaltwo-dimensional profile is, for example, a ring, the outside diameterthereof will be enlarged by the amount of the offset but the insidediameter thereof will be reduced by the amount of the offset. In otherwords, the outline is shifted outward by the amount of the offset.

The reason for carrying out this offset expansion processing is asfollows. To wit, as will be described below, whether each LED 51 isturned on or off is determined based on the value of the pixel at thecenter of each light spot. For this reason, if the turning on and off ofthe LEDs 51 were to be carried out using the two-dimensional profiledata from the workstation 7 as is without further modification, therewould be a smaller number of light spots available to expose the pixelsin the vicinity of the outline (edge) of the two-dimensional profile(the reason for this being that light spots having centers in pixelsoutside of the outline are turned off), preventing full benefit of theabove-described multiple exposure from being obtained. An offset istherefore applied and the outline moved outward so that all of the lightspots having centers in pixels within a 0.5 mm-diameter range centeredon this pixel will be turned on, even for pixels residing on the outlineof the two-dimensional profile. Accordingly, the standard value for theoffset is the radius of the light spot, or 0.25 mm. However, because theideal value for the offset will depend on curing characteristics of theresin, adjustment of the time during which the light spot is lit, and soforth, it is preferable to allow arbitrary setting of the offset,including the possibility of setting negative values therefor.

The two-dimensional profile data expanded by means of the aboveprocessing is called contour data. Next, the control computer 3 convertsthis contour data into a 1,024-bit×1,024-bit bitmapped image 87. Thevalue of each bit of this bitmapped image 87 is such that, for example,a value of 1 means that the LED should be turned on (pixel cured) whilea value of “0” means that the LED should be turned off (pixel not cured)(of course, the reverse is also possible).

Next, the control computer 3 allows the exposing head 23 to startscanning, and while scanning is being carried out the values of bitsfrom the bitmapped image 87 are read, a luminescent pattern is created,and the LED light source 37 is driven based thereon (S5).

The luminescent pattern is created according to the following method. Weshall assume that the optical fibers 55 are arrayed in 8 rows of 128fibers, as shown in FIG. 4. Furthermore, as shown in FIG. 9, we shalluse coordinates (p,q) at the exposing head 23 to identify each of theoptical fibers 55. Here, the number p (p=0 to 7) is the number of therow (p=0 to 7) of each of the optical fiber subarrays 63 <1> through 63<8>, while the number q (q=0 to 127) is a number indicating the positionof each of the optical fibers 55 within each of the optical fibersubarrays. Furthermore, we shall express the position in the X-axisdirection (scan direction) of each of the optical fiber subarrays 63 <1>through 63 <8> at the exposing head 23 as a multiple Np which is thedistance between the first-row optical fiber subarray 63 <1> and each ofthe optical fiber subarrays 63 <1> through 63 <8> divided by the pixelpitch 62.5 μm. For example, for the first-row subarray 63 <1> (p=0),N0=0; for the second-row subarray 63 <2> (p=1), N1=8 (i.e., the distancefrom the first-row subarray is 0.5 mm); for the third-row subarray 63<3> (p=2), N2=18 (i.e., the distance from the second-row subarray is0.625 mm); and so forth. Furthermore, we shall use coordinates (i,j)within the exposure region 24 (bitmapped image 87) to identify each ofthe pixels 71. Here, the numbers i and j respectively indicate rownumber (X coordinate) and column number (Y coordinate) within thebitmapped image 87. Moreover, scanning of the exposing head 23 iscarried out by means of a method wherein the exposing head 23 moves inthe X-axis direction in increments of one 62.5-μm pixel pitch at a time,and we shall express the time t during scanning as t=0 at the start ofscanning and as t=m at a time thereafter when the exposing head 23 hasmoved a distance equivalent to m pixel pitches.

Given the above assumptions, the control computer 3 turns on and off anLED 51 connected to an optical fiber 55 at coordinates (p,q) at a time tduring scanning based on the value of the pixel at coordinates (i,j) asdetermined according to the following formulas (however, note that theLED 51 is defined as being turned off when i assumes a negative value oris 1,024 or greater):

i=t−Np

j=p+8×q

For example, at scanning start time t=0, the first-row optical fibersubarray 63 <1> (p=0, Np=0) is positioned at the exposure startposition. At this time, a luminescent pattern is created for only thisfirst-row optical fiber subarray 63 <1> (i is negative for thesecond-row and following subarrays). That is, a luminescent pattern iscreated for the pixel values at coordinates (0,0), (0,8), (0,16), . . .(0,1016) as determined from the above formulas for the LEDs 51 of therespective optical fibers 55 at position numbers q=0, 1, 2, . . . 127 inthis first row.

Thereafter, a luminescent pattern as determined from the above formulasis created for only the first-row subarray 63 <1> at respective timest=1, 2, . . . 7.

At time t=8, when the exposing head 23 has moved a distance equivalentto 8 pixel pitches from the start of scanning, the second-row opticalfiber subarray 63 <2> (p=1, Np=8) arrives at the exposure startposition. From this time forward, a luminescent pattern is created forthe first-row subarray 63 <1> and the second-row subarray 63 <2> (i isnegative for the third-row and following subarrays). That is, aluminescent pattern is created for the pixel values at coordinates(8,0), (8,8), (8,16), . . . (8,1016) as determined from the aboveformulas for the respective LEDs 51 at position numbers q=0, 1, 2, . . .127 in the first row, and a luminescent pattern is created for the pixelvalues at coordinates (0,1), (0,9), (0,17), . . . (0,1017) as determinedfrom the above formulas for the respective LEDs 51 at position numbersq=0, 1, 2, . . . 127 in the second row.

Thereafter, a luminescent pattern as determined from the above formulasis created for only the first-row and second-row subarrays 63 <1>, 63<2> at respective timest=9, 10, . . . 17.

At time t=18, when the exposing head 23 has moved a distance equivalentto 18 pixel pitches from the start of scanning, the third-row opticalfiber subarray 63 <3> (p=2, Np=18) arrives at the exposure startposition. From this time forward, a luminescent pattern is created forthe first-row subarray 63 <1>, the second-row subarray 63 <2>, and thethird-row subarray 63 <3> (i is negative for the fourth-row andfollowing subarrays). This luminescent pattern is also determinedaccording to the above formulas.

Hereinafter, each time that the exposing head 23 advances a distanceequivalent to a single pixel pitch, a luminescent pattern is likewisecalculated from the above formulas and the appropriate LEDs are turnedon. Moreover, the above control operations are repeated until i ascalculated from the above formulas reaches 1,023 (or until the maximumvalue of i for which the pixel value thereof is “1” is reached) for theeighth-row optical fiber subarray 63 <8>, this marking the end ofexposure of one layer.

Upon completion of exposure of one layer, the control computer 3 lowersthe elevator 15 by an amount equivalent to the thickness of one layer,and exposure is again carried out according to a similar controlprocedure for the next layer. This is repeated until the layer at thetop of the solid model is reached.

FIG. 10 shows an example of another constitution for the LED lightsource 37 which may be used in the present embodiment.

In this constitution, an LED lamp such as is shown in FIG. 3 is notused, but rather a light source is employed wherein a multiplicity ofsolid-state luminescent elements, typically LED chips 92, are formed (ormounted) in, for example, matrix fashion on a semiconductor substrate(or an insulating substrate of appropriate material) 91. Furthermore,one end of each optical fiber 93 is arranged directly above each LEDelement 92 so as to be extremely proximate to or in contact with eachLED element 92. The tip of each optical fiber 93 is guided to theexposing head 23. This constitution permits the light emitted by LEDelements 92 to be captured by the optical fibers 93 more efficientlythan is the case with a constitution employing the lamp shown in FIG. 3.

While a preferred embodiment of the present invention has been describedabove, this embodiment has been presented only as an example fordescribing the present invention, the intention thereof not being tolimit the present invention to this embodiment alone. The presentinvention may be carried out in any number of modes in addition thereto.

What is claimed is:
 1. A solid model creation apparatus comprising: atank that holds a photocurable resin solution; an exposure regioncomprising a two-dimensional set of a multiplicity of pixels set withinsaid photocurable resin solution in said tank; an exposure apparatusthat irradiates light onto said exposure region; and a control apparatusthat controls said exposure apparatus so as to cure a selected pixelwithin said exposure region; wherein said exposure apparatus possessesat least one light spot generator capable of being switched on and off,said light spot generator irradiating said exposure region with a lightspot larger in size than each of the pixels when turned on, and saidexposure region is scanned by said light spot generator, and, while saidlight spot generator is scanning said exposure region, said controlapparatus turns on the sum total plurality of said light spot generatorspresent at locations permitting irradiation of said selected pixel withsaid light spot.
 2. A solid model creation apparatus according to claim1 wherein said exposure apparatus possesses a plurality of light spotgenerators that irradiate said exposure region with a plurality of lightspots arrayed in the primary scan direction at a first pitch smallerthan the diameter of said light spots, and said exposure region isscanned in the secondary scan direction with this plurality of lightspot generators.
 3. A solid model creation apparatus according to claim2 wherein said first pitch is equal to the pitch of said pixels.
 4. Asolid model creation apparatus according to claim 2 wherein saidexposure apparatus possesses at least two light spot generatorsubarrays, each comprising at least two light spot generators lined upin a single row in said primary scan direction at a second pitch largerthan said first pitch, and these light spot generator subarrays arethemselves arranged in said secondary scan direction with a displacementtherebetween in said primary scan direction which is equal to said firstpitch.
 5. A solid model creation apparatus according to claim 1 whereinsaid control apparatus 1) receives data indicating the cross-sectionalprofile of a solid model and generates a modified cross-sectionalprofile by applying a prescribed offset to this data, and 2) while saidlight spot generator is scanning said exposure region, turns on saidlight spot generator when the center of said light spot from said lightspot generator is at a location contained within said modifiedcross-sectional profile.
 6. A solid model creation apparatus accordingto claim 1 wherein said light spot generator possesses solid-stateluminescent element as a light source.
 7. A solid model creationapparatus according to claim 6 wherein said solid-state luminescentelement is an LED.
 8. A solid model creation apparatus according toclaim 6 wherein said solid model creation apparatus further possesses anoptical fiber connected to said solid-state luminescent element, and thetip of said optical fiber is contained within said light spot generator.9. A solid model creation apparatus according to claim 6 wherein saidlight spot generator further possesses a GRIN lens that receives lightfrom said solid-state luminescent element and forms said light spot. 10.A solid model creation apparatus according to claim 7 wherein said LEDis a blue LED.
 11. A solid model creation method comprising: receivingcontrol data indicating a two-dimensional cross-sectional profile foreach layer of a plurality of layers of the solid model; and for eachlayer, scanning an exposure region comprising a two-dimensional set ofpixels in a photocurable resin solution with light spots that are eachlarger than respective pixels, wherein each respective pixel isirradiated by light spots originating from a plurality of locationsaccording to said control data.
 12. A solid model creation methodaccording to claim 11 wherein said exposure region is scanned in across-section direction by a plurality of said light spots, and saidplurality of light spots are arrayed in a primary scan direction in saidexposure region at a first pitch smaller than the diameter of said lightspots.
 13. A solid model creation method according to claim 12 whereinsaid first pitch is equal to the pitch of said pixels.
 14. A solid modelcreation method according to claim 12 wherein said plurality of lightspots comprise at least two light spot subarrays, each comprising atleast two of said light spots lined up in a single row in said primaryscan direction at a second pitch larger than said first pitch, and saidlight spot subarrays are arranged in said secondary scan direction witha displacement therebetween in said primary scan direction which isequal to said first pitch.
 15. A solid model creation method accordingto claim 11 that comprises generating a modified cross-sectional profileby applying a prescribed offset to said control data, wherein saidexposure region is irradiated at locations contained within saidmodified cross-sectional profile.
 16. A solid model creation methodaccording to claim 11 wherein the light source for said light spot is asolid-state luminescent element.
 17. A solid model creation methodaccording to claim 16 wherein said solid-state luminescent element is anLED.
 18. A solid model creation method according to claim 17 whereinsaid LED is a blue LED.
 19. A solid model creation apparatus comprising:a tank that holds a photocurable resin solution, wherein an exposureregion within the photocurable resin solution comprises a plurality ofpixels; an exposure apparatus comprising at least one light spotgenerator that cures pixels of resin within the tank by irradiating theexposure region with light spots that are each larger than respectivepixels; and a control apparatus that, in response to control data,controls the exposure apparatus to irradiate a respective pixel by lightspots originating from a plurality of locations.
 20. A solid modelcreation apparatus according to claim 19 wherein the exposure apparatuspossesses a plurality of light spot generators that irradiate theexposure region with a plurality of light spots arrayed in a primaryscan direction at a first pitch smaller than the diameter of the lightspots, and the exposure region is scanned in a secondary scan directionwith this plurality of light spot generators.
 21. A solid model creationapparatus according to claim 20 wherein the first pitch is equal to thepitch of the pixels.
 22. A solid model creation apparatus according toclaim 20 wherein the exposure apparatus possesses at least two lightspot generator subarrays, each comprising at least two light spotgenerators lined up in a single row in the primary scan direction at asecond pitch larger than the first pitch, and these light spot generatorsubarrays are themselves arranged in the secondary scan direction with adisplacement therebetween in the primary scan direction which is equalto the first pitch.
 23. A solid model creation apparatus according toclaim 19 wherein the control apparatus 1) receives data indicating across-sectional profile of the solid model and generates a modifiedcross-sectional profile by applying a prescribed offset to this data,and 2) while the light spot generator is scanning the exposure region,turns on the light spot generator when the center of the light spot fromthe light spot generator is at a location contained within the modifiedcross-sectional profile.
 24. A solid model creation apparatus accordingto claim 19 wherein the light spot generator possesses solid-stateluminescent element as a light source.
 25. A solid model creationapparatus according to claim 24 wherein the solid-state luminescentelement is a light emitting diode (LED).
 26. A solid model creationapparatus according to claim 24 wherein the solid model creationapparatus further possesses an optical fiber connected to thesolid-state luminescent element, and the tip of the optical fiber iscontained within the light spot generator.
 27. A solid model creationapparatus according to claim 24 wherein the light spot generator furtherpossesses a gradient index (GRIN) lens that receives light from thesolid-state luminescent element and forms the light spot.
 28. A solidmodel creation apparatus according to claim 25 wherein the LED is a blueLED.